Keywords: wind energy, wind turbines, wind power plants, electrical power system, operating costs, ancillary services, ancillary services costs, unit-commitment horizon, load-following horizon, regulation horizon, wind variability
A summary of wind power impacts on electric power system operating costs
Wind power plant output depends on wind speed. Such speeds cannot be accurately predicted over daily periods because the wind fluctuates from minute-to-minute and hour-to-hour. Consequently, electric utility system planners and operators are concerned that variations in wind plant output may increase the operating costs of the system. This concern arises because the system must maintain balance between the aggregate demand for electric power and the total power generated by all power plants feeding the system. The operators' concerns are compounded because unlike conventional power plants that are generally under their control and thus are dispatchable, the wind plants are controlled by nature. It should be understood that the key issue is not whether a system with a significant amount of wind capacity can be operated reliably, but rather to what extent the system operating costs are increased by the variability of the wind.